Louisiana Pass http://www.louisianapass.org/
(Sample link) National Geographic for Kids http://www.nationalgeographic.com/kids/
NASA for Middle School Students http://www.nasa.gov/audience/forstudents/5-8/index.html
Brain Pop http://www.brainpop.com
Ask Jeeves for Kids http://www.askforkids.com/
Fun Brain http://www.funbrain.com
PBS Kids http://www.pbskids.org
Newton http://www.newton.k12.ks.us/tech/fourth_grade_internet_activities1.htm
Math Frog http://cemc2.math.uwaterloo.ca/mathfrog/english/kidz/Games4.shtml
Fraction Games http://www.iknowthat.com/com/L3?Area=FractionGame
Math Games http://www.internet4classrooms.com/skills_4th_math.htm
Reading and Math Activities http://www.indianhillselementary.net/sites/4th.htm